Tracked machines, such as tractors and excavators, include an undercarriage system for propelling the machines on ground. The undercarriage system includes track links that are coupled to track shoes. The track shoes are embodied as ground contacting members. Each track link is coupled with the respective track shoe by a pair of track bolts. During initial coupling, the track bolts are tightened under a certain amount of clamping force so that the track bolts do not loosen during machine operation. However, the track bolts have a tendency to elongate over time, resulting in loss of clamping force. The loss in clamping force affects stress in a bolted joint between the track link and track shoe, which is not desirable. Thus, the track bolts are periodically checked for elongation and thereby the clamping forces.
U.S. Pat. No. 9,488,212 describes a dust proof structure for a stress-sensible screw is provided. The dust proof structure includes a sensing screw, a head, a dust proof boot and a displayer. The sensing screw includes a base and at least one exposed lead, and the exposed lead is located in the base and transmits a stress signal. The head includes a lead base, the head is fitted with the base, and the exposed lead is detachably connected to the lead base. The dust proof boot is disposed on the head, and sleeves a connecting portion between the lead base and the exposed lead. The displayer is electrically connected with the head for displaying the stress signal.